The invention is a velocipede—defined as a lightweight wheeled vehicle propelled by the rider—in combination with a pair of hand-grasped poles by which it is propelled. The vehicle has just two wheels, which are aligned one following the other, referred to herein as two-wheel tandem. The bicycle and the scooter are examples of a two-wheel tandem vehicle that appear very different, however both have the essential “two-wheeler” configuration that is commonly believed to include a handlebar. In the invention the riders' hands are totally engaged with the poles, and do not come in contact with the vehicle at all; and therefor surprisingly, the vehicle is a two-wheeler without a handlebar. Poles on the other hand, have been suggested before as a means of propulsion in a lightweight wheeled vehicle.
Poles which have traditionally been used with skis are also used for balance and propulsion of skis to which wheels have been added to navigate hard surfaces (U.S. Pat. Nos. 2,545,543; and 3,389,922). Poles have been provided to the users of roller skates for control, balance, and thrust (see, for example, WO 932588 and U.S. Pat. No. 5,601,299). Wheeled vehicles that allow the user to stand, sit, or kneel can be propelled by poles. Poles used like oars can propel such a vehicle (U.S. Pat. Nos. 1,313,157; 1,425,220; 1,619,668; and 2,216,982). A single (U.S. Pat. Nos. 1,052,722; and 2,005,910) or multiple poles (U.S. Pat. Nos. 3,310,319; and 5,098,087) can also be used that are independent from the vehicle for propulsion as well as brakes on coasting vehicles. While some of these devices are designed to assist the movement of paraplegics, most of the subject devices are intended for recreational use and to have fun.
Hwang, U.S. Pat. No. 5,125,687, described a rollerboard for road-skiing. The rollerboard has a rear wheel along a longitudinal line of the board, a front caster and subsidiary rollers to stabilize the platform. The user can either stand or sit on the platform. Poles are used to change direction of the board. Chern, U.S. Pat. No. 4,863,182, attached a skate to a unicycle to create a sporting device that could be used traditionally as a unicycle by pedaling or as an ice or grass scooter with poles to facilitate the sliding movement. A variety of vehicles in a variety of configurations to include two, three, four and more wheels have been designed for use with poles, however, a two-wheel tandem vehicle does not appear among them.
In spite of the poles and lack of handlebars, the present invention still must conform to those same configurational requirements which all two-wheelers have in common, the ones that make it possible for a person to balance upon a moving frame supported by just two wheels on the road. Steering a two-wheel tandem vehicle is part of an active process by which the rider maintains their balance on the vehicle. And as such, the vital function of controlling the steering wheel by the use of the rider's upper limbs, that is so integral to this process, must now be accomplished by some other method, which the invention does by the following scheme: The lower half of the rider's body is used to perform those functions which the upper half traditionally did by the use of handlebars, that is, stabilize the rider on the vehicle and steer its forward wheel; so then the upper half of the body is free to be used to propel the vehicle, which is what the lower half normally did.
Although hands-free steering of a two-wheeler may have been thought theoretically possible, such means or method has not heretofore proved to be feasible. Barachet's (U.S. Pat. No. 5,160,155) proposed “Skateboard Having Two Wheels in Tandem” with its caster-mounted (where the wheel's point-of-contract with the road is aft of the steering axis) forward wheel may be such an attempt. Bryant, U.S. Pat. No. 6,488,295, also proposed a way that a two-wheeler might be modified to enable it to be operated hands-free. Other experts, those skilled in the art, may offer their opinions—yet none can be found that would declare that it is not possible—nevertheless, as far as can be determined by this inventor, it has not before now been successfully demonstrated.
In the year 1896, some twenty years or so into the development of the modern bicycle, Bicycles & Tricycles was published in England and became the foremost authoritative reference source on the design of the bicycle. Archibald Sharp, the author, analyzed every aspect of bicycle design, including the phenomenon of riding one without holding the handlebar. Economy of words, regarded as an attribute in writing during that period, can make Sharp's explanation on “Steering Without Hands” difficult to follow; however it does appear, the knowledge and understanding of the two-wheel tandem vehicle, as it pertains to the present invention, has not advanced since then.
Sharp presents four pages of analysis with diagrams and equations that take into account the factors involved with steering a bicycle without the use of the hands. Sharp assumes a rider can maintain equilibrium without touching the handlebar provided torque at the steering axis stays balanced; and therefore, forces acting on the front wheel and frame, which may tend to turn it about the steering axis, must be controlled by the rider. Sharp recognizes two such forces which can cause various moments about the steering axis that tend to cause the position of the front wheel to deviate from its mid-position (front and rear wheels heading in the same direction) whenever the vehicle is tilted. One moment is due to the wheel's point-of-contract with the road being out of alignment with that plane which includes the rear wheels' point-of-contact and the steering axis. The force that is associated with this “first moment” is a reaction to that weight which bears on the front wheel.
A “second moment” is due to the center-of-mass—of that weight which pivots about the steering axis itself—being offset from the steering axis. The force associated with said second moment is caused by the pull-of-gravity on this mass, which includes the weight of the front wheel, fork, and anything else attached thereto, like a handlebar for instance. The two moments tend to act in the same direction. A “third moment”, which opposes or counter-balances the other two, is produced by centripetal force at the front wheel's point-of-contract with the road, and is a reaction to the turning motion of the vehicle as it is being ridden. The centripetal force so generated is at right angle to the direction of travel; and hence at any given moment in time, this force is along the radius of the turn and in a direction pointing into the center of the turn.
Sharp derives an analytical expression for each of the three moments which take into account those factors mentioned above. According to Sharp: “To maintain equilibrium the [summation of the analytical expressions for the three moments] should have the value zero, to steer further to one side or other it should have a small positive value, and to steer straighter a small negative value.” Sharp then points out: “For given values of speed and steering angle, there remains an element, the inclination of the rear-frame, at the command of the rider; but even with a skilled rider the above moment varies probably so quickly that he could not adjust the inclination quickly enough to preserve equilibrium.” It appears Sharp had little confidence that the factors in this part of his analysis explained the feasibility of riding a bicycle without using the handlebar.
The 1890's were the golden age of bicycle design. Sharp and a handful of other highly regarded bicycle experts of the time—most notable, Sharp's prominent French contemporary M. Bourlet—spent a great deal of effort attempting to explain the secret of the two-wheel tandem vehicle. Agreement was never reached regarding the “no-hands” phenomenon. And over the following century little if any improvement in the bicycle's basic design, or advancement in understanding, were made. In 1977 the MIT Press republished Sharp's Treatise, and in the foreword David Gordon Wilson, professor of mechanical engineering at the school, says this “definitive work . . . marked, and helped to bring about, the end of an exciting period in mechanical engineering . . . and was almost the last book as well as the last word on bicycle design.”
In today's modern era, those skilled in the art still hold the prevailing opinion from that earlier period. In U.S. Pat. No. 6,488,295 Bryant states: “Particularly skilled riders can maintain stable, dynamic balance of traditional bicycles traveling straight without holding the handlebars. In such cases, they may even be able to turn their bicycles left or right simply by leaning their body and tilting the vehicle. However, minor transient disturbances, such as those associated with riding on an uneven or rough road surface, or the rider needing to change speed or steering directions, quickly destabilize the vehicle”. Bryant asserts: “for any given two-wheeled vehicle, there is a controllable operating envelope of speeds and turn radii for a given terrain in which the rider's ability to simply tilt the vehicle in one direction or the other is sufficient to correct dynamic instabilities arising during operation of the vehicle”, but because that “envelope is much smaller than desired . . . traditional two-wheeled vehicles are hand-steered”. Bryant believes that he knows a way to correct this condition and thereby eliminate the need for handlebars.
Bryant's apparent revelation: “A previously unrecognized, but major factor in two-wheeled vehicle stability is the un-stabilizing force associated with the point-of-contact of the steering wheel, which is pivotally secured to the vehicle along the steering axis, being spaced too far away from the vehicle plane, defined as the plane that includes the rear wheel's point-of-contact and the steering axis, when the steering wheel is turned” is of course the very same force recognized by Sharp and presented in his 1896 Treatise, as cited herein, and that being the cause of said “first moment” referred to above. And like Sharp before him, Bryant realizes that this “major factor” can generate torque about the steering axis. Bryant does not, however, recognize Sharp's “second moment” which can also cause torque about the steering axis.
Bryant does not attempt to improve the hands-free handling capability of the bicycle in general. Bryant's objective is to take a given two-wheeled vehicle and make it stable and controllable within an “operational envelope”—and eliminate the necessity for a handlebar—by incorporating a “dynamic control regulator” which, by mechanical means, can vary the geometry of the vehicle as a function of its tilt and steering angle. Bryant's proposes several designs for such a vehicle where “the rider stands on a substantially planar standing surface in the same manner as a rider of a surfboard, snowboard, or skateboard” and steers by leaning their body in the same hands-free manner.
Interestingly, in his discussion of the state-of-the-art, Bryant refers to the 1995 second edition of Bicycling Science—where the same David Wilson that helped get Sharp's 1896 book republished, and who concludes in his book: “the balancing and steering of bicycles is an extremely complex subject on which there is a great deal of experience and rather little science”—as “another example of the limitations found with conventional analysis of two-wheeled vehicles.” Archibald Sharp, Carlo Bourlet, David Wilson and Robert Bryant can all be considered experts on steering and stability of a two wheel tandem vehicle, however they do not form a consensus on the subject. Although many experts in the engineering and design of the bicycle have studied and analyzed the topic of steering and balance, the fact remains, over this long period, as far as known, nobody has succeeded in making a rideable two-wheel tandem vehicle that operates without a handlebar.
In his third edition of Bicycling Science, in which Wilson comments on why he decided to have Jim Papadopoulos write the chapter on steering and balancing—“the chapter on the topic that I wrote for the second edition . . . was the least satisfactory in the book”—Wilson remarks that over the years he has “found, through sending the drafts out to experts for review, that there seemed to be no agreement among experts on the topic.” Papadopoulos, who is “a graduate of MIT with a Ph.D. in mechanical engineering, some-one who has devoted his life to the improvement of scientific and engineering knowledge of bicycles and bicycling”, writes in the introduction of the chapter: “Unfortunately, the mathematics purporting to describe bicycle motion and self-stability are difficult and have not been validated experimentally, so design guidance remains highly empirical.” At the end of the chapter, Papadopoulos cites thirty seven references, including Sharp and three other experts from a hundred plus years earlier, in support of this finding.
All patents, patent applications, provisional patent applications and publications referred to or cited herein, are incorporated by reference in their entirety to the extent they are not inconsistent with the teachings of the specification.